- GCN/BACODINE POSITION NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Tue 15 Sep 15 21:19:43 UT
NOTICE_TYPE: Swift-BAT GRB Position
TRIGGER_NUM: 655721, Seg_Num: 0
GRB_RA: 319.731d {+21h 18m 55s} (J2000),
319.971d {+21h 19m 53s} (current),
318.964d {+21h 15m 51s} (1950)
GRB_DEC: -34.854d {-34d 51' 12"} (J2000),
-34.787d {-34d 47' 12"} (current),
-35.065d {-35d 03' 53"} (1950)
GRB_ERROR: 3.00 [arcmin radius, statistical only]
GRB_INTEN: 0 [cnts] Image_Peak=1208 [image_cnts]
TRIGGER_DUR: 64.000 [sec]
TRIGGER_INDEX: 20000 E_range: 15-50 keV
BKG_INTEN: 0 [cnts]
BKG_TIME: 0.00 SOD {00:00:00.00} UT
BKG_DUR: 0 [sec]
GRB_DATE: 17280 TJD; 258 DOY; 15/09/15
GRB_TIME: 76704.86 SOD {21:18:24.86} UT
GRB_PHI: 121.40 [deg]
GRB_THETA: 24.62 [deg]
SOLN_STATUS: 0x13
RATE_SIGNIF: 0.00 [sigma]
IMAGE_SIGNIF: 7.23 [sigma]
MERIT_PARAMS: +1 +0 +0 +6 +1 -3 +0 +0 +71 +0
SUN_POSTN: 173.31d {+11h 33m 14s} +2.89d {+02d 53' 28"}
SUN_DIST: 135.56 [deg] Sun_angle= -9.8 [hr] (East of Sun)
MOON_POSTN: 200.15d {+13h 20m 37s} -6.52d {-06d 31' 01"}
MOON_DIST: 109.94 [deg]
MOON_ILLUM: 6 [%]
GAL_COORDS: 9.53,-44.33 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 311.25,-18.26 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: SWIFT-BAT GRB Coordinates.
COMMENTS: This is an image trigger. (The RATE_SIGNIF & BKG_{INTEN, TIME, DUR} are undefined.)
COMMENTS: A point_source was found.
COMMENTS: This does not match any source in the on-board catalog.
COMMENTS: This does not match any source in the ground catalog.
COMMENTS: This is a GRB.
COMMENTS: This trigger occurred at longitude,latitude = 20.04,15.40 [deg].
- red DSS finding chart
ps-file
- GCN NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Tue 15 Sep 15 21:21:12 UT
NOTICE_TYPE: Swift-XRT Position
TRIGGER_NUM: 655721, Seg_Num: 0
GRB_RA: 319.6579d {+21h 18m 37.89s} (J2000),
319.8985d {+21h 19m 35.63s} (current),
318.8901d {+21h 15m 33.62s} (1950)
GRB_DEC: -34.9130d {-34d 54' 46.7"} (J2000),
-34.8462d {-34d 50' 46.4"} (current),
-35.1240d {-35d 07' 26.3"} (1950)
GRB_ERROR: 4.8 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN: 5.57e-09 [erg/cm2/sec]
GRB_SIGNIF: 12.52 [sigma]
IMG_START_DATE: 17280 TJD; 258 DOY; 15/09/15
IMG_START_TIME: 76833.55 SOD {21:20:33.55} UT, 128.7 [sec] since BAT Trigger Time
TAM[0-3]: 327.66 237.21 261.63 243.48
AMPLIFIER: 2
WAVEFORM: 134
SUN_POSTN: 173.31d {+11h 33m 14s} +2.89d {+02d 53' 27"}
SUN_DIST: 135.48 [deg] Sun_angle= -9.8 [hr] (East of Sun)
MOON_POSTN: 200.16d {+13h 20m 39s} -6.52d {-06d 31' 13"}
MOON_DIST: 109.85 [deg]
MOON_ILLUM: 6 [%]
GAL_COORDS: 9.44,-44.28 [deg] galactic lon,lat of the burst
ECL_COORDS: 311.17,-18.30 [deg] ecliptic lon,lat of the burst
COMMENTS: SWIFT-XRT Coordinates.
COMMENTS: The XRT position is 5.06 arcmin from the BAT position.
COMMENTS: The object found at this position is either a very bright burst or a cosmic ray hit.
COMMENTS: Examine the XRT Image to differentiate (CRs are much more compact); see examples at:
COMMENTS: http://www.swift.psu.edu/xrt/XRT_Postage_Stamp_Image_Photo_Gallery.htm .
- GCN Circular #18315
V. D'Elia (ASDC), N. Gehrels (NASA/GSFC), L. Izzo (URoma/ICRA),
F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL) and M. H. Siegel (PSU)
report on behalf of the Swift Team:
At 21:18:24 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150915A (trigger=655721). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 319.731, -34.854 which is
RA(J2000) = 21h 18m 55s
Dec(J2000) = -34d 51' 12"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). As is usual for an image trigger, there
is no obvious variation in the immediately available BAT lightcurve.
The XRT began observing the field at 21:20:33.5 UT, 128.7 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 319.65874,
-34.91306 which is equivalent to:
RA(J2000) = 21h 18m 38.10s
Dec(J2000) = -34d 54' 47.0"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 301 arcseconds from the BAT onboard position. This position
may be improved as more data are received; the latest position is
available at http://www.swift.ac.uk/sper.
Although this position is outside the nominal 90% BAT error circle,
it is probably the GRB.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (8.65 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 2.7
(+2.23/-1.97) x 10^21 cm^-2 (90% confidence).
The initial flux in the 2.5 s image was 5.57e-09 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 133 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag.
The 8'x8' region for the list of sources generated on-board covers 19% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.10.
Burst Advocate for this burst is V. D'Elia (delia AT asdc.asi.it).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)
- GCN NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Tue 15 Sep 15 21:43:50 UT
NOTICE_TYPE: Swift-XRT Position UPDATE
TRIGGER_NUM: 655721, Seg_Num: 0
GRB_RA: 319.6588d {+21h 18m 38.11s} (J2000),
319.8994d {+21h 19m 35.85s} (current),
318.8910d {+21h 15m 33.84s} (1950)
GRB_DEC: -34.9131d {-34d 54' 47.1"} (J2000),
-34.8463d {-34d 50' 46.8"} (current),
-35.1241d {-35d 07' 26.7"} (1950)
GRB_ERROR: 3.6 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN: 1.00e-10 [erg/cm2/sec]
GRB_SIGNIF: 10.00 [sigma]
IMG_START_DATE: 17280 TJD; 258 DOY; 15/09/15
IMG_START_TIME: 77077.00 SOD {21:24:37.00} UT, 372.1 [sec] since BAT Trigger Time
TAM[0-3]: 100.00 100.00 100.00 100.00
AMPLIFIER: 1
WAVEFORM: 31
SUN_POSTN: 173.32d {+11h 33m 18s} +2.88d {+02d 53' 05"}
SUN_DIST: 135.47 [deg] Sun_angle= -9.8 [hr] (East of Sun)
MOON_POSTN: 200.34d {+13h 21m 23s} -6.57d {-06d 34' 29"}
MOON_DIST: 109.68 [deg]
MOON_ILLUM: 6 [%]
GAL_COORDS: 9.44,-44.28 [deg] galactic lon,lat of the burst
ECL_COORDS: 311.17,-18.30 [deg] ecliptic lon,lat of the burst
COMMENTS: SWIFT-XRT Coordinates.
COMMENTS: This Notice was ground-generated -- not flight-generated.
COMMENTS: This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.
COMMENTS: TAM values, flux and significance fields are not valid.
COMMENTS: This position was automatically generated on the ground using
COMMENTS: Photon Counting data telemetered via TDRSS (SPER data).
COMMENTS: See http://www.swift.ac.uk/sper/docs.php for details.
COMMENTS: The probability that this is a serendipitous source in the
COMMENTS: SPER window is 0.58% < P(seren) < 1.1%.
- GCN Circular #18316
R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias
V. Lipunov, E. Gorbovskoy, N.Tyurina, V.Kornilov,
P.Balanutsa, A.Kuznetsov, D.Kuvshinov, E.Popova
Lomonosov Moscow State University, Sternberg Astronomical Institute
K.Ivanov, O.Gres, N.M.Budnev, S.Yazev,
Irkutsk State University
D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory
A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik
Kislovodsk Solar Station of the Pulkovo Observatory
V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov, A.Gabovich
Blagoveschensk Educational State University, Blagoveschensk
V.Krushinski, I.Zalozhnih
Ural Federal University, Kourovka
Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
Claudio Mallamaci, Carlos Lopez and Federico Podest
Observatorio Astronomico Felix Aguilar (OAFA)
MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru)
located in IAC (Tenerife, Spain) was pointed to the GRB150915A 22 sec
after notice time and 95 sec after trigger time at 2015-09-15 21:20:03 UT
in two polarizations. On our first single (20s exposure) and coadd (760s
exposure) sets we haven`t found optical transient within SWIFT error-box
(Elia et al. GCN 18315).
The 5-sigma upper limit has been about 17.3 on single and 19.8 on coadd
image.
MASTER II robotic telescope located in SAAO (South Africa) was pointed to
the GRB150915A 25 sec after notice time and 100 sec after trigger time at
2015-09-15 21:20:07 UT in two polarizations. On our first (20s exposure)
set we haven`t found optical transient within SWIFT error-box .
The 5-sigma upper limit has been about 17.2 mag
The message may be cited.
- GCN Circular #18317
R. Yates, J. Bolmer and J. Greiner (all MPE Garching) report on behalf of
the GROND team:
We observed the field of GRB 150915A (D'Elia et al., GCN 18315) simultaneously
in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at
the 2.2 m MPG telescope at ESO La Silla Observatory (Chile). Observations
started at 23:28 UT on 2015-09-15, 2.2 hours after the GRB trigger.
Based on a 42 minutes exposure at a mid-time of 3.7 hours after the BAT
trigger, at an average seeing of 1.6" and at an average airmass of 1.0,
we detect an optical counterpart at the edge of the Swift-XRT error-circle at
RA = 21 18 37.84
Decl. = -34 54 48.3
(+/- 0.3")
at the following with magnitudes (AB system)
g' = 23.0 +/- 0.1 mag,
r' = 23.1 +/- 0.1 mag,
i' = 22.9 +/- 0.2 mag,
z' = 22.7 +/- 0.2 mag,
J > 19.9 mag,
H > 19.3 mag,
K > 17.9 mag.
The given magnitudes are derived based on calibrating the images against
GROND zeropoints in the optical and 2MASS in the NIR, and are not corrected
for the expected Galactic foreground extinction corresponding to a reddening
of E_(B-V) = 0.10 mag in the direction of the burst (Schlegel et al. 1998).
- GCN Circular #18318
V. D'Elia (ASI/ASDC and INAF-OAR), T. Kruehler (MPE), D. Xu (NAOC/CAS), Pall Jakobsson (Univ. Iceland), N. R. Tanvir (U. Leicester), A. de Ugarte Postigo (IAA/CSIC), D. Malesani (DARK/NBI) and J. P. U. Fynbo (DARK/NBI), report on behalf of a larger collaboration:
We observed the optical counterpart of GRB 150915A (D'Elia et al., GCN 18315) with the ESO VLT equipped with the X-shooter spectrograph. Four spectra with individual exposure time of 1200 s were secured covering the wavelength range 3,000-21,000 AA. Spectroscopy began 3.3 hr after the BAT trigger. The afterglow is well detected in our acquisition image at the position of the optical counterpart (Yates et al., GCN 18317).
We detect a number of absorption features at a common redshift of z = 1.968, including Ly-a, C IV, Al II, Si II, Fe II, Mg II. We also detect fine-structure lines at the same redshift (e.g. FeII* 2396 / 2389, and Si II* 1533). Finally, we report strong emission lines of [O II], H-alpha and H-beta at a similar redshift, thus confirming z=1.968 as the GRB/host galaxy redshift.
We thank the kind assistence of the observing staff at Paranal, in particular Steve Ertel.
- GCN Circular #18322
A. A. Breeveld (UCL-MSSL) and V. D'Elia (ASDC) report on behalf of the
Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 150915A
295s after the BAT trigger (D'Elia et al., GCN Circ. 18315).
No optical afterglow consistent with the XRT position (D=E2=80=99Elia et =
al.,
GGN Circ. 18315) or the GROND position (Yates et al., GCN Circ. 18317)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding
chart (FC) exposure and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
u_FC 295 545 246 >20.0
white 576 769 39 >19.9
v 625 818 39 >18.2
b 550 745 39 >19.2
u 295 4267 434 >20.0
The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) =3D 0.10 in the direction of th=
e
burst (Schlegel et al. 1998).
- GCN Circular #18323
D. Xu (NAOC/CAS), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), N. R.
Tanvir (Univ. Leicester), D. Malesani (DARK/NBI), T. Kruehler (MPE),
P. Jakobsson (Univ. Iceland), S. Schulze (PUC, MAS), V. D'Elia
(ASI/ASDC and INAF-OAR), K. Karhunen (Turku Univ.), report on behalf
of a larger collaboration:
We observed the field of GRB 150915A (D'Elia et al., GCN 18315) with
the Nordic Optical Telescope equipped with the ALFOSC camera. Two
observations composed each by 3x300 s exposures in R-band were taken
with the mean times of 0.80 and 3.05 hr after the GRB trigger.
The source detected by GROND and reported by Yates et al. (GCN 18317)
is clearly visible in our images at both epochs, with a magnitude of
R(Vega) = 22.52 +- 0.09 on our first epoch (assuming R = 16.72 for the
star at RA = 21:18:34.76, Dec = -34:53:44.9).
Interestingly, the object is found to brighten between the two epochs
by 0.28 +- 0.11 mag - a behavior not common, though not unprecedented.
- GCN Circular #18325
K. L. Murata (Nagoya U.), S. Nagatomo (Kyoto U.), and T. Nagayama (Kagoshima U.)
We observed the field of GRB150915A (D'Elia et al., GCN Circular #18315) with the near-infrared (J, H, Ks) simultaneous
imaging camera SIRIUS attached to 1.4 m telescope IRSF ( InfraRed Survey Facility) in Sutherland observatory, South Africa.
The observations started on 2015-09-15 23:45:25 UT (~ 2.5 hours after the burst).
We could not detect the afterglow within the XRT error circle reported in the GCN circular in the three bands.
We have obtained the following preliminary upper limits (Vega magnitude system):
J > 16.47
H > 15.91
Ks > 15.64.
Given magnitudes were calibrated against 2MASS point sources in this field.
The upper limits were determined as the magnitudes of the faintest star within 1 arcmin from the XRT position.
This observation was carried out by IRSF and OISTER collaboration.
- GCN Circular #18328
D. M. Palmer (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
V. D'Elia (ASDC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150915A (trigger #655721)
(D'Elia, et al., GCN Circ. 18315). The BAT ground-calculated position is
RA, Dec = 319.675, -34.874 deg which is
RA(J2000) = 21h 18m 42.0s
Dec(J2000) = -34d -52' -27.1"
with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 55%.
The mask-weighted light curve shows a weak complex structure that starts
at ~ T0-70 s and ends at ~T0+120 s. There might be additional weak emission
that starts since the beginning of the event data. T90 (15-350 keV)
is 164.7 +- 49.7 sec (estimated error including systematics).
The time-averaged spectrum from T-69.0 to T+116.8 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
2.51 +- 0.42. The fluence in the 15-150 keV band is 8.0 +- 1.8 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+17.68 sec in the 15-150 keV band
is 0.5 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/655721/BA/
- GCN Circular #18329
A. D'ai (INAF-IASFPA), A. Maselli (INAF-IASFPA), A. Melandri
(INAF-OAB), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), D.N.
Burrows (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester),
L. Izzo (URoma/ICRA) and V. D'Elia (ASDC) report on behalf of the
Swift-XRT team:
We have analysed 12 ks of XRT data for the Swift/BAT-detected burst GRB
150915A (D'Elia et al. GCN Circ. 18315), from 118 s to 126.0 ks after
the Swift/BAT trigger. The data comprise 256 s in Windowed Timing (WT)
mode (the first 8 s were taken while Swift was slewing) with the
remainder in Photon Counting (PC) mode. The refined XRT position is RA,
Dec = 319.6584, -34.9136 which is equivalent to:
RA (J2000): 21 18 38.01
Dec(J2000): -34 54 49.1
with an uncertainty of 3.7 arcsec (radius, 90% confidence). This
position is 5.1 arcmin from the Swift/BAT position.
The light curve can be modelled with an initial power-law decay with an
index of alpha=0.5 (+/-0.3), followed by a break at T+170 s to an alpha
of 3.94 (+0.15, -0.13).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.79 (+/-0.04). The
best-fitting absorption column is 7.8 (+1.7, -1.6) x 10^21 cm^-2, at a
redshift of 1.968, in addition to the Galactic value of 8.6 x 10^20
cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed)
0.3-10 keV flux conversion factor deduced from this spectrum is 3.7 x
10^-11 (4.5 x 10^-11) erg cm^-2 count^-1.
A summary of the WT-mode spectrum is thus:
Galactic foreground: 8.6 x 10^20 cm^-2
Intrinsic column: 7.8 (+1.7, -1.6) x 10^21 cm^-2 at z=1.968
Photon index: 1.79 (+/-0.04)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00655721.
This circular is an official product of the Swift-XRT team.
- 1605.04274 from 16 May 16
C. R. A. Augusto et al.: Prompt emission from GRB 150915A in the GeV energy range detected at ground by the New-Tupi detector
Since 2014, a new detector (New-Tupi) consisting of four plastic scintillators ($150 \times 75 \times 5 cm^3$) placed in pairs and located in
Niteroi, Rio de Janeiro, Brazil, has been used for the search of transient solar events and photomuons from gamma-ray bursts (GRBs). On
September 15, 2015, at 21:18:24 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 150915A (trigger 655721). The GRB light
curve shows a weak complex structure of long duration $T_{90}=164.7 \pm 49.7 $ sec, and a fluence in the 15-150 keV band of $8.0 \pm 1.8 \times
10^{-7}erg/cm^2$. GRB 150915A was fortuitously located in the field of view of the New-Tupi detector, and a search for prompt emission in the
GeV energy range is presented here. The analysis was made using the "scaler" or "single-particle" technique. The New-Tupi detector registered a
muon excess peak of 6.1s duration with a signal significance $6.9\sigma$, the signal was within the T90 duration of the Swift BAT GRB, with an
estimated fluence $4.8 \times 10^{-6} erg/cm^2$ (10-100 GeV). The Poisson probability of the event to be a background fluctuation is $6.9
\times 10^{-10}$ and it appears in the counting rate of the New-Tupi detector with an annual rate $\sim 2.6$.
Previous IAU Circulars 